Mud scraper



United States Patent 3,176,771 MUD SCRAPER Marshall L. Claiborne, 200 W. Alto, Hobbs, N. Mex., and Edward G. Durrett, PD. Box 866, Odessa, Tex. Filed Nov. 28, 1962, Ser. No. 240,612 6 Claims. ((31. 166-473) This invention relates to wells and more particularly to cementing casing within wells.

Often casing is cemented within wells. If the well was drilled with a rotary rig and drilling mud introduced, there is a problem with a mud cake upon the side of the bore within the ground which prevents a good adhesion between the cement and the formation around it. Also there exists a problem of the cement channeling as it is being pumped into the well. In addition, it is desirable to have the casing centered within the well.

We have invented a device for removing the mud cake, centralizing the casing, and preventing the cement from channeling as it is introduced into the Well. Thisacts somewhat similar to the device disclosed by M. L. Claiborne, one of the coinventors here, in US. Patent 3,044,- 552, issued July 17, 1962.

An object of this invention is to provide a device for the above purposes.

Still further objects are to achieve the above with a device that is sturdy, compact, durable, simple, and reliable, yet inexpensive and easy to manufacture.

The specific nature of the invention as well as other objects, uses, and advantages thereof will clearly appear from the following description and from the accompanying drawing, the different views of which are not necessarily to the same scale, in which:

FIG. 1 is an elevational view of the device on casing within the well.

FIG. 2 is a perspective view of one spiral member.

As may be seen in the drawings, the device in operation is attached to casing 10. The device includes upper right hand spiral member 12 and lower left hand spiral member 14. The spirals each include band 16 at either end which surrounds the casing 10. The inside diameter of the band 16 is slightly larger than the outside diameter of the casing so that the band is free to rotate. Between the bands there are two helical vanes of flat metal 18 so that a double helix is formed. Each vane makes one complete revolution between the top band 16 and lower band 16. The metal of the vanes extends radially outward from the axis of the casing or spiral. In practice we have found useful dimensions to make each spiral approximately 18 inches long. Therefore for about six inch casing this results in a helical angle of about 45 degrees. I.e. the vane will make a 45 degree angle with a diametrical plane at all points. The inside of the vane 18 forms a smooth fit around the cylindrical outsides of the casing 10. There is sufiicient clearance so that the members 12 and 14 rotate freely on the casing Ill.

The upper spiral 12 and lower spiral 14 are held in place by weld bands 20, 22, and 24. Each of the weld bands have four holes through them by which they are spot welded as at 26 to the casing 10. The lower weld band 20 is first placed on the casing and welded in place, then the left hand spiral member 14 is placed on the casing, and then the middle weld band 22 is placed upon the casing, and spaced a short distance, e.g. 2 inches above the band 16 of the bottom spiral member 14. It likewise is spot-. welded in place by welds through holes in it. The upper spiral member 12 is put in place and the upper weld band 24 is attached, again allowing clearance above the top band 16. Thus the spiral members are mounted for limited translational movement on the casing 10.

The width of the straps forming the vanes 18 are suili- 3,176,771 latented Apr. 6, 1965 cient so that the vanes will contact the side wall of the bore within the earth when it is lowered in place. As seen in the drawing the vanes 18 project uniformly from the casing 10 and project as far from the casing as any element attached to the casing.

In use the device is attached to the casing 10 at convenient intervals along the casing at that point where the easing will be opposite the strata within the ground where it is particularly desirable for the cement to form a good bond with the wall of the well bore.

As the casing Ill is lowered into the well the straps of the vanes 18 will cause the mud to be removed from the side of the well. The spiral members 12 and 14 will rotate somewhat around the casing 10, however, due to the fact that there has been no eifort to reduce friction this rotation will by no means be perfect and a great amount of scraping action will result. If there is an obstruction within the well, it will not block the passage of the casing 10 within the well or cause the scraper to be torn up inasmuch as the members 12 and 14 will rotate around the axis of the casing 10 to pass by the obstruction within the well.

When all the casing 10 is assembled and in place the device will be opposite the formation where it is desired for a particularly good bond to be obtained. Then as the cement is pumped through the casing, there will be a flow within the casing and outside within the annular space between the casing 10 and the bore. During this time the casing 10 is reciprocated as is common practice in the art. This reciprocating action will result in thorough cleansing of the formation where the scrapers are located. The scrapers will rotate to some extent but not completely due to the friction and vibration due to the fact that there is a loose fit of the device upon the casing 10. Naturally they will centralize the casing within the bore as they have t the same radial spacing all the way around.

Also the flow of fluid caused by the pumping of the cement within the casing will cause the vanes 18 to rotate about the casing 10. This rotation will aid. in the removal of the mud at that point. Also this rotation will tend to agitate both the mud and the cement preventing the possibilities of channels forming. There is no possibility of leaving a vertical channel or vein of mud along one side of the casing 10.

It will be apparent that the embodiment shown is only exemplary and that various modfications can be made in construction, materials, and arrangement within the scope of the invention as defined in the appended claims.

We claim as our invention:

1. A mud scraper mounted on casing comprising:

(a) a lower band attached around the casing,

(b) a lower spiral member surrounding the casing above the lower band,

(0) the lower spiral member having helical vanes extending radially outward from the casing,

(d) the lower spiral member mounted for rotational and translational movement on the casing,

(e) a middle band attached around the casing above the lower spiral member,

(1) an upper spiral member surrounding the casing above the middle band,

(g) the upper spiral member having vanes extending radially outward from the casing which rotate around the casing in the opposite direction than the vanes of the lower spiral,

(h) the upper spiral member mounted for rotational and translational movement on the casing, and

(i) an upper band attached around the casing above the upper spiral member.

2. A mud scraper mounted on casing comprising:

(a) an upper spiral member surrounding the casing,

(b) the upper spiral member having helical vanes eX tending radially outward from the casing,

(c) the upper spiral member mounted for free rotational movement on the casing,

(d) the upper spiral member mounted for limited translational movement on the casing, and

(e) a lower spiral member surrounding the casing,

(f) the lower spiral member having helical vanes extending radially outward from the casing which rotate around the casing in the opposite direction than the vanes of the upper spiral member,

(g) the lower spiral member mounted for free rotational movement on the casing, and

(h) the lower spiral member mounted for limited translational movement on the casing.

3. A mud scraper mounted on casing comprising:

(a) an upper spiral member surrounding the casing,

(b) the upper spiral member having helical vanes extendingv radially outward from the casing,

(c) the upper spiral member mounted for free rotational movement on the casing,

(d) the upper spiral member mounted for limited translational movement on the casing, and

(e) a lower spiral member surrounding the casing,

(f) the lower spiral member having helical vanes extending radially outward from the casing which rotate around the casing in the opposite direction than the vanes of the upper spiral member.

(g) the lower spiral member mounted for free rotational movement on the casing, and

(h) the lower spiral member mounted for limited translational movement on the casing,

(j) each spiral member having a length of at least three times the diameter of the casing,

(k) each helical vane making at least one full revolution, and

(m) means on the casing for limiting the translational movement to less than the diameter of the casing.

4. The invention as defined in claim 3 wherein (n) said vanes project uniformly from the casing and project as far away from the casing as any element attached to the casing.

5. A mud scraper mounted on casing comprising:

(a) a lower band attached around the casing,

(b) a lower spiral member surrounding the casing above the lower band,

(c) the lower spiral member having helical vanes extending radially outward from the casing,

(d) the lower spiral member mounted for rotational and translational movement on the casing,

(e) a middle band attached around the casing above the lower spiral member,

(7) an upper spiral member surrounding the casing above the middle band,

(g) the upper spiral member having vanes extending radially outward from the casing which rotate around the casing in the opposite direction than the vanes of the lower spiral,

(h) the upper spiral member mounted for rotational and translational movement on the casing,

(i) an upper band attached around the casing above the upper spiral member,

(j) each spiral member having a length of at least thre times the diameter of the casing,

(k) each helical vane making at least one full revolution, and

(m) the spacing of the lower band, the middle band' and upper band such that the translational movement of the spiral members is limited to less than the diameter of the casing.

6. The invention is defined in claim 5 wherein (n) said vanes project uniformly from the casing and project as far away from the casing as any element attached to the casing.

References Cited by the Examiner UNITED STATES PATENTS 1,677,050 7/28 Reed et al 166-175 1,755,762 4/30 Armstrong et al. 166-175 1,810,260 6/31 Swinford 166175 2,352,412 6/44 Sandstone 166241 2,515,149 7/50 Willhoit 166--241 2,679,905 6/54 Mangum et al. 166-175 3,044,552 7/ 62 Claiborne -s 166-170 3,072,195 1/63 Kluck 166-177 X 3,083,772 4/63 Tripplehorn 166176 CHARLES OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner. 

2. A MUD SCRAPER MOUNTED ON CASING COMPRISING: (A) AN UPPER SPIRAL MEMBER SURROUNDING THE CASING, (B) THE UPPER SPIRAL MEMBER HAVING HELICAL VANES EXTENDING RADIALLY OUTWARD FROM THE CASING, (C) THE UPPER SPIRAL MEMBER MOUNTED FOR FREE ROTATIONAL MOVEMENT ON THE CASING, (D) THE UPPER SPIRAL MEMBER MOUNTED FOR LIMITED TRANSLATIONAL MOVEMENT OF THE CASING, AND (E) A LOWER SPIRAL MEMBER SURROUNDING THE CASING, (F) THE LOWER SPIRAL MEMBER HAVING HELICAL VANES EXTENDING RADIALLY OUTWARD FROM THE CASING WHICH ROTATE AROUND THE CASING IN THE OPPOSITE DIRECTION THAN THE VANES OF THE UPPER SPIRAL MEMBER, (G) THE LOWER SPIRAL MEMBER MOUNTED FOR FREE ROTATIONAL MOVEMENT ON THE CASING, AND (H) THE LOWER SPIRAL MEMBER MOUNTED FOR LIMITED TRANSLATIONAL MOVEMENT ON THE CASING. 